Timestamp extension for In Situ Operations, Administration, and Maintenance (IOAM) Direct Export

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Table of Contents

1. Introduction

Network operators wish to measure the On-Path delay across their networks to understand which part of the network causes how much delay and impact which applications. Network nodes can leverage IOAM [RFC9197] to add timestamps into the packet and export the raw data with [I-D.spiegel-ippm-ioam-rawexport] or the calculated On-Path delay with [I-D.ietf-opsawg-ipfix-on-path-telemetry] to the IPFIX [RFC7011] collector.¶

In order to support Postcard-Based On-Path delay measurement, IOAM Direct Export Option-type (DEX) [RFC9326] needs to be extended with timestamps to accommodate delay monitoring.¶

This document defines two new Extension fields for IOAM DEX Option-type [RFC9326] to support an optional timestamp in the header.¶

2. Solution overview

The IOAM DEX Option-type format is defined in Section 3.2 [RFC9326]. To be able to measure the delay between the IOAM encapsulation node and the current IOAM node, the timestamp is added to the IOAM DEX option-type as illustrated in Figure 1.¶

This document proposes two optional fields to be included in the IOAM DEX option type format so that they can be enabled using IOAM DEX Extension-Flags. New Extension-Flags are allocated by IANA, as defined in Section 7. This document proposes using the bit 2 for the Timestamp Seconds and the bit 3 for the Timestamp Fraction.¶

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Namespace-ID           |     Flags     |Extension-Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|               IOAM-Trace-Type                 |   Reserved    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Flow ID (Optional)                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Sequence Number  (Optional)               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                   Timestamp Seconds  (Optional)               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                  Timestamp Fraction  (Optional)               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

While the Timestamp Seconds field can be used standalone, the Timestamp Fraction MUST be used in combination with the Timestamp Seconds field.¶

3. Timestamp Formats

The Timestamp Seconds and Timestamp Fraction field encoding format definitions are described in Section 5 of [RFC9197].¶

4. Export Method

While the Timestamp Seconds and Timestamp Fraction can be exported via IOAM raw export using [I-D.spiegel-ippm-ioam-rawexport] and the calculated On-Path delay can be exported using IPFIX with [I-D.ietf-opsawg-ipfix-on-path-telemetry], the mechanism and associated formats for exporting the delay metrics are outside the scope of this document.¶

5. Use Cases

Possible interesting On-Path delay measurement use cases in combination with other key metrics is described in Section 5 of [I-D.ietf-opsawg-ipfix-on-path-telemetry].¶

6. Security Considerations

The security considerations for the IOAM DEX Option-type are described in [RFC9326]. This document adds no additional security considerations.¶

7. IANA Considerations

This document requests IANA to create the following two bits in the "IOAM DEX Extension-Flags" registry.¶

  Bit: 2
  Description: Timestamp Seconds
  Reference: this document

  Bit: 3
  Description: Timestamp Fraction
  Reference: this document

8. Acknowledgements

The authors would like to thank xxx for their review and valuable comments.¶

Authors' Addresses